Rotation angle detection devices for detecting a relative angle or an absolute angle of a rotation angle detection target are used in automotive drive motors for, for example, electric power steering devices. It is also conceivable to apply the rotation angle detection devices to bearings used in various devices required to be rotationally controlled. For example, Patent Literature 1 describes a rotation angle detection device-equipped bearing integrally incorporating a rotation angle detection device. The rotation angle detection device described in Patent Literature 1 includes a rotating body provided with a plurality of magnetic tracks provided with mutually different numbers of magnetic poles arranged at even intervals in a concentric ring configuration and a plurality of magnetic sensors for detecting respective magnetic fields of these magnetic tracks, and the rotating body is mounted on a rotary shaft of a rotor of an automotive drive motor or on a member that rotates integrally with the rotary shaft. The rotation angle detection device detects a rotor angle of the automotive drive motor. With this configuration, the rotation angle detection device can be compactly incorporated without increasing the axial dimension of the automotive drive motor.